The objective of this program is to perform a study on the influence of reinforcement materials on the properties of dental composite restoratives. This will be accomplished by making a systematic study of the influence of shape, size, and type. Specifically, the use of shaped particle fillers, such as flakes and fibers with favorable length to thickness ratio, as compared to other regular or irregular particles, will be investigated to attain formulas for optimal dental requirements. Much information has been developed in other technological areas showing the superiority of two dimensional reinforcements (flakes/fibers) in composite materials over other configurations (i.e. spherical or irregular shaped particles) and with regard to strength, modulus, water sorption, wear resistance, and dimensional stability. It should be possible to apply this knowledge to obtain a vastly improved dental composite restorative system. This study involves treating the two dimensional reinforcing filler particles, determining methods for optimum orientation of the reinforcement in the composite system, fabricating appropriate test specimens, and conducting a complete evaluation of the composite system.